1. Field of the Invention
The present invention relates generally to receptacles having cylindrical bodies, in particular those cylinders that are formed of metal and are secured at both ends to heads that typically are also formed of metal.
In a more particular sense, the invention comprises a metallic receptacle, and a method of making said receptacle, wherein the cylinder or barrel comprises a helically wound panel or panels, adjacent longitudinal edges of which are crimped into engagement with each other, with the ends of the panels being similarly crimped or rolled into a secure connection to the peripheries of the drum heads.
2. Description of the Prior Art
Containers of the drum type having cylindrical barrels crimped into engagement with the peripheries of the container ends, the barrels being formed of helically wound strips, are known in and of themselves. However, those containers in which the barrels are helically wound are of fibrous or paperboard stock, which presents no particular difficulties in winding the same into a helical form, and in thereafter roll-forming or crimping the resulting ends of the cylindrical body portion into engagement with container ends that in some instances are formed wholly of metallic material.
When drum type containers must be formed of metal (as is true, for example, of large containers in which heavy flowable materials are shipped), the methods used for manufacturing container barrels of fibrous stock must be discarded. Typically, conventional metal shipping drums comprise tubular barrels to which flat ends are attached to form the complete drum. Usually, the barrel is formed by welding a flat sheet of metal into a hoop shape and then deforming (or reforming) the hoop so that it will remain generally circular in cross-section. The weld joint extends in parallel relation to the drum axis. In even older forms of shipping drums or containers, the joint was closed by rivets.
In such containers, the heads have in general been attached to the barrel by means of welds, clamps, or by rolled or crimped seams. A typical crimped or rolled joint for a head of a container of this type is of a double overlap type, with the drum head being slightly recessed. A flowable sealant often fills the crimped seam for the purpose of preventing leakage.
Conventional practice imposes certain limitations in the manufacture of the barrels. Ordinarily the material used is a low-carbon, uncoated steel. Though other metals may be utilized, they offer a progressively greater scale of difficulty, especially with respect to the welded joints. Welding, indeed, precludes the use of pre-coated materials, since the heat required in the welding step destroys almost all available coatings. As a result, the conventional practice is to apply coatings after manufacture, and this has produced problems both with respect to quality control and to cost.
Another problem that has been encountered with respect to conventional metal drums of the type described above has to do with the tendency toward damage resulting from forcible impact of one drum against another during transportation. In conventional practice, most drums have two or three "rolling rings" formed in the barrel. These are used to maintain circularity. In a typical casualty situation, a small space develops between adjacent drums. An external force may be applied, as a result of which the drums tip, the present rings pass each other, and thereafter come into contact with the softer intermediate plating. Since the rings are deliberately stiff, the intermediate plating is deformed, often leading to major damage to the drum and possible loss of the cargo.